Kelly passed away in her sleep at age 43 on Wednesday night, reported TMZ. The cause of the death is not immediately clear, but she was at a rehab facility after voluntarily checking herself in for treatment for an alcohol problem last week.

“She had been fighting demons for a while and finally lost her battle,” her agent said.

Sources told TMZ that emergency responders found needle marks on Kelly’s arms but her new boyfriend said that the needle marks are from nurses making multiple attempts to insert a needle into her vein to extract blood when the boyfriend took her to a hospital on Sunday, prior to helping her check into rehab on Monday.

The actress had been arrested at least 4 times in the past 3 years for driving under intoxication, spousal abuse, and assault.

She had filed for divorce from her husband Robert Gilliam in July.

Kelly played Laurie Forman, the older sister of Eric Forman, in the immensely popular and long-running “That 70’s Shows,” a television series about life in the 1970’s in America.

She acted in 50 episodes over five years of the show, which played ran from 1998 through 2006 and additional years through re-runs on various stations. Kelly acted in the series from 1998 through 2003.

One of her co-stars, Danny Masterson, whose character Steven Hyde was sometimes a love interest of Laurie’s, said on Twitter that Kelly’s death was “terrible, awful news.”